Associations between Serum Apelin-12 Levels and Obesity-Related Markers in Chinese Children

Objective: To investigate possible correlations between apelin-12 levels and obesity in children in China and associations between apelin-12 and obesity-related markers, including lipids, insulin sensitivity and insulin resistance index (HOMA-IR). Methods: Forty-eight obese and forty non-obese age-and gender-matched Chinese children were enrolled between June 2008 and June 2009. Mean age was 10.42 +/- 2.03 and 10.86 +/- 2.23 years in obesity and control groups, respectively. Main outcome measures were apelin-12, BMI, lipids, glucose and insulin. HOMA-IR was calculated for all subjects. Results: All obesity group subjects had significantly higher total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), insulin levels and HOMA-IR (all P<0.05). In separate analyses, obese girls had significantly higher LDL-C, insulin and HOMA-IR than controls, and obese boys had significantly higher TC, TG, insulin and HOMA-IR than controls (all P<0.05). Apelin-12 levels were significantly higher in obese girls compared to controls (P = 0.024), and correlated positively with TG in all obese subjects. Among obese girls, apelin-12 levels correlated positively with TG, insulin and HOMA-IR after adjusting for age and BMI. In all boys (obese and controls) apelin-12 was positively associated with fasting plasma glucose (FPG). No significant correlations were found in either group between apelin-12 levels and other characteristics after adjusting for age, sex, and BMI. Conclusions: Apelin-12 levels are significantly higher in obese vs. non-obese girls in China and correlate significantly with obesity-related markers insulin, HOMA-IR, and TG. Increased apelin-12 levels may be involved in the pathological mechanism of childhood obesity.